Submission #966744

#	Time	Username	Problem	Language	Result	Execution time	Memory
966744		Soumya1	Circle selection (APIO18_circle_selection)	C++17	100 / 100	1018 ms	36944 KiB

circle_selection

#include <bits/stdc++.h>
using namespace std;
const int mxN = 3e5 + 5;
int x[mxN], y[mxN], r[mxN], ans[mxN];
bool intersect(int a, int b) {
  return 1LL * (x[a] - x[b]) * (x[a] - x[b]) + 1LL * (y[a] - y[b]) * (y[a] - y[b]) <= 1LL * (r[a] + r[b]) * (r[a] + r[b]);
}
int block;
vector<int> all[mxN];
vector<pair<int, int>> vv;
int n;
int get(pair<int, int> p) {
  auto it = lower_bound(vv.begin(), vv.end(), p);
  if (it != vv.end() && *it == p) return it - vv.begin();
  return -1;
}
void scale() {
  vv.clear();
  for (int i = 0; i < n; i++) all[i].clear();
  for (int i = 0; i < n; i++) {
    if (ans[i]) continue;
    vv.push_back({x[i] / block, y[i] / block});
  }
  sort(vv.begin(), vv.end());
  vv.erase(unique(vv.begin(), vv.end()), vv.end());
  for (int i = 0; i < n; i++) {
    if (ans[i]) continue;
    all[get({x[i] / block, y[i] / block})].push_back(i);
  }
}
void testCase() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> x[i] >> y[i] >> r[i];
  }
  vector<int> ord(n);
  iota(ord.begin(), ord.end(), 0);
  sort(ord.begin(), ord.end(), [&](int i, int j) {
    if (r[i] != r[j]) return r[i] > r[j];
    return i < j;
  });
  block = r[ord[0]];
  scale();
  for (int i : ord) {
    if (ans[i]) continue;
    if (2 * r[i] < block) {
      block = r[i];
      scale();
    }
    for (int xx = x[i] / block - 2; xx <= x[i] / block + 2; xx++) {
      for (int yy = y[i] / block - 2; yy <= y[i] / block + 2; yy++) {
        auto id = get({xx, yy});
        if (id == -1) continue;
        for (int j = 0; j < all[id].size(); ) {
          if (intersect(i, all[id][j])) {
            ans[all[id][j]] = i + 1;
            swap(all[id][j], all[id].back());
            all[id].pop_back();
          } else {
            j++;
          }
        }
      }
    }
  }
  for (int i = 0; i < n; i++) cout << ans[i] << " ";
  cout << "\n";
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  testCase();
  return 0;
}

Compilation message (stderr)

circle_selection.cpp: In function 'void testCase()':
circle_selection.cpp:54:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |         for (int j = 0; j < all[id].size(); ) {
      |                         ~~^~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 12 / 12
• Subtask 3: 15 / 15
• Subtask 4: 23 / 23
• Subtask 5: 30 / 30
• Subtask 6: 13 / 13